We introduce a new selected configuration interaction plus perturbation theory algorithm that is based on deterministic analog of our recent efficient heat-bath sampling algorithm. This Heat-bath Configuration Interaction (HCI) makes use two parameters control the trade-off between speed and accuracy, one which controls selection determinants to add variational wave function used compute perturbative correction energy. show HCI provides an accurate treatment both static dynamic correlation...

We extend the recently proposed heat-bath configuration interaction (HCI) method [Holmes, Tubman, Umrigar, J. Chem. Theory Comput. 2016, 12, 3674], by introducing a semistochastic algorithm for performing multireference Epstein-Nesbet perturbation theory, in order to completely eliminate severe memory bottleneck of original method. The has several attractive features. First, there is no sign problem that plagues quantum Monte Carlo methods. Second, instead using Metropolis-Hastings sampling,...

We use the recently-developed Heat-bath Configuration Interaction (HCI) algorithm as an efficient active-space solver to perform multi-configuration self-consistent field calculations (HCISCF) with large active spaces. give a detailed derivation of theory and show that difficulties associated non-variationality HCI procedure can be overcome by making Lagrangian formulation calculate relaxed two body reduced density matrix. HCISCF is then used study electronic structure butadiene, pentacene,...

We introduce a semistochastic implementation of the power method to compute, for very large matrices, dominant eigenvalue and expectation values involving corresponding eigenvector. The is in that matrix multiplication partially implemented numerically exactly with respect only. Compared fully stochastic method, approach significantly reduces computational time required obtain specified statistical uncertainty. This demonstrated by application quantum Monte Carlo systems sign problem:...

This paper presents in detail our fast semistochastic heat-bath configuration interaction (SHCI) method for solving the many-body Schrodinger equation. We identify and eliminate computational bottlenecks both variational perturbative steps of SHCI algorithm. also describe parallelization key data structures implementation, such as distributed hash table. The improved algorithm enables us to include wavefunction two orders magnitude more determinants than has been reported previously with...

The electronically excited states of methylene (CH$_2$), ethylene (C$_2$H$_4$), butadiene (C$_4$H$_6$), hexatriene (C$_6$H$_8$), and ozone (O$_3$) have long proven challenging due to their complex mixtures static dynamic correlations. Semistochastic heat-bath configuration interaction (SHCI), which efficiently systematically approaches the full (FCI) limit, is used provide close approximations FCI energies in these systems. This article presents largest FCI-level calculation date -- on using...

We extend our recently developed heat-bath configuration interaction (HCI) algorithm, and semistochastic algorithm for performing multireference perturbation theory, to calculate excited-state wavefunctions energies. employ time-reversal symmetry, which reduces the memory requirements by more than a factor of two. An extrapolation technique is introduced reliably extrapolate HCI energies full CI limit. The resulting used compute fourteen low-lying potential energy surfaces carbon dimer using...

We introduce an algorithm for sampling many-body quantum states in Fock space. The efficiently samples with probability approximately proportional to arbitrary function of the second-quantized Hamiltonian matrix element connecting sampled state current state. apply new recently-developed Semistochastic Full Configuration Interaction Quantum Monte Carlo method (S-FCIQMC), a semistochastic implementation power projecting out ground energy basis Slater determinants. heat-bath requires modest...

Quantum computers are growing in size, and design decisions being made now that attempt to squeeze more computation out of these machines. In this spirit, we a method boost the computational power nearterm quantum by adapting protocols used error correction implement "Approximate Error Correction (AQEC):" By approximating fully-fledged mechanisms, can increase compute volume (qubits $\times$ gates, or "Simple Volume (SQV)") near-term The crux our is fast hardware decoder approximately decode...

The authors use the recently developed semistochastic heat bath configuration interaction method to calculate potential energy curve of very challenging Cr${}_{2}$ dimer. Despite fact that largest Hilbert space has dimension ${10}^{42}$, paper obtains energies with estimated errors a few mHa or less.

Quantum computing hardware is undergoing rapid development from proof-of-principle devices to scalable machines that could eventually challenge classical supercomputers on specific tasks. On platforms with local connectivity, the transition one- two-dimensional arrays of qubits seen as a natural technological step increase density power and reduce routing cost limited connectivity. Here we map schedule representative algorithmic workloads—the Fourier Transform (QFT) relevant factoring,...

Effective quantum computation relies upon making good use of the exponential information capacity a machine. A large barrier to designing algorithms for execution on real machines is that, in general, it intractably difficult construct an arbitrary state high precision. Many rely instead initializing machine simple state, and evolving through efficient (i.e. at most polynomial-depth) algorithm. In this work, we show that there exist families states can be prepared precision with circuits...

The control of cryogenic qubits in today’s super-conducting quantum computer prototypes presents significant scalability challenges due to the massive costs generating/routing analog signals that need be sent from a classical controller at room temperature chip inside dilution refrigerator. Thus, researchers industry and academia have focused on designing in-fridge controllers order mitigate these challenges. Due maturity CMOS logic, many industrial efforts (Microsoft, Intel)...

Quantum computing (QC) is at the cusp of a revolution. Machines with 100 quantum bits (qubits) are anticipated to be operational by 2020 [30, 73], and several-hundred-qubit machines around corner. this scale have capacity demonstrate supremacy, tipping point where QC faster than fastest classical alternative for particular problem. Because error correction techniques will central most expensive component computation, choosing lowest-overhead scheme critical overall success. This paper...

Quantum computing (QC) offers huge promise to accelerate a range of computationally intensive benchmarks. is limited, however, by the challenges decoherence: i.e., quantum state can only be maintained for short windows time before it decoheres. While error correction codes protect against decoherence, fast execution best defense so efficient architectures and effective scheduling algorithms are necessary. This paper proposes Multi-SIMD QC architecture then evaluates schedulers map benchmark...

Compiling high-level quantum programs to machines that are size constrained (i.e. limited number of bits) and time operations) is challenging. In this paper, we present SQUARE (Strategic QUantum Ancilla REuse), a compilation infrastructure tackles allocation reclamation scratch qubits (called ancilla) in modular programs. At its core, strategically performs uncomputation create opportunities for qubit reuse. Current Noisy Intermediate-Scale Quantum (NISQ) computers forward-looking...

Quantum computers have recently made great strides and are on a long-term path towards useful fault-tolerant computation. A dominant overhead in quantum computation is the production of high-fidelity encoded qubits, called magic states, which enable reliable error-corrected We present first detailed designs hardware functional units that implement space-time optimized magic-state factories for surface code machines. Interactions among distant qubits require braids (physical pathways chip)...

Variational algorithms are a representative class of quantum computing workloads that combine and classical computing. This paper presents an LLVM-based C++ compiler toolchain to efficiently execute variational hybrid quantum-classical on computational system in which the device acts as accelerator. We introduce set extensions language for programming these algorithms. define novel Executable Linking Format (ELF) Quantum create component LLVM framework compile part source reuse host source....

Quantum computing (QC) offers huge promise to accelerate a range of computationally intensive benchmarks. is limited, however, by the challenges decoherence: i.e., quantum state can only be maintained for short windows time before it decoheres. While error correction codes protect against decoherence, fast execution best defense so efficient architectures and effective scheduling algorithms are necessary. This paper proposes Multi-SIMD QC architecture then evaluates schedulers map benchmark...

Amyloid beta, an intrinsically disordered protein, plays a seemingly important but not well-understood role in neurodegenerative diseases like Alzheimer's disease. A key feature of amyloid which could lead to potential therapeutic intervention pathways, is its binding affinity certain metal centers, iron and copper. Numerically calculating such affinities computationally challenging task, involving strongly correlated centers. bottleneck understanding the obtaining estimates ground state...

Recent estimates indicate that the U.S. Department of Defense spends over \$20 billion USD annually on corrosion-related maintenance. This expenditure is accompanied by a substantial loss in asset readiness, ranging from 10% to 30%. Moreover, global costs associated with corrosion damage have been estimated at an astonishing \$2.5 trillion per year, or approximately 3.4% GDP 2016. project aims describe how quantum computers might be leveraged fundamentally change way material-environment...

Effective quantum computation relies upon making good use of the exponential information capacity a machine. A large barrier to designing algorithms for execution on real machines is that, in general, it intractably difficult construct an arbitrary state high precision. Many rely instead initializing machine simple state, and evolving through efficient (i.e. at most polynomial-depth) algorithm. In this work, we show that there exist families states can be prepared precision with circuits...

As computer architecture continues to expand beyond software-agnostic microarchitecture data center organization, reconfigurable logic, heterogeneous systems, application-specific and even radically different technologies such as quantum computing, detailed cycle-level simulation is no longer presupposed. Exploring designs under complex interacting relationships (e.g., performance, energy, thermal, cost, voltage, frequency, cooling leakage, etc.) calls for a more integrative but higher-level...

We demonstrate how to determine numerically nearly exact orthonormal orbitals that are optimal for the evaluation of energy arbitrary (correlated) states atoms and molecules by minimization Lagrangian. Orbitals expressed in real space using a multiresolution spectral element basis is refined adaptively achieve user-specified target precision while avoiding ill-conditioning issues plague AO set expansions traditionally used correlated models molecular electronic structure. For light atoms,...